1. Technical Field
The present invention relates to a tongue assembly for use in a vehicle seat belt system for restraining movement of an occupant of a vehicle.
2. Description of the Prior Art
A known type of vehicle seat belt system is a three-point continuous loop seat belt system. A three-point continuous loop seat belt system includes a seat belt retractor and a length of belt webbing. The belt webbing extends from the retractor through a D-ring fixed to the vehicle and then down to an anchor point near the vehicle floor. A tongue assembly is slidable along the length of belt webbing between the D-ring and the anchor point. The tongue assembly includes a clamping mechanism for clamping the belt webbing. To use the seat belt system, a vehicle occupant grasps the tongue assembly and inserts it into a buckle. When the tongue assembly is fastened in the buckle, a portion of the belt webbing extends across the lap of the vehicle occupant and a portion of the belt webbing extends diagonally across the torso of the vehicle occupant. The clamping mechanism clamps the belt webbing and blocks movement of the belt webbing through the tongue assembly.
When the tongue assembly is engaged with the buckle, the lap and torso portions of the belt webbing are clamped in the clamping mechanism of the tongue assembly. The clamping mechanism of a typical tongue assembly extends across the width of the tongue assembly, transverse to a plane extending longitudinally through the tongue assembly between the leading end or latching portion of the tongue assembly and the trailing end portion of the tongue assembly. The lap and torso portions of the belt webbing extend from the trailing end portion of the tongue assembly. The belt webbing portions preferably extend straight back from the trailing end portion of the tongue assembly--that is, parallel to the above-mentioned plane. If this is the case, the belt webbing portions can extend from the clamping mechanism of the tongue assembly at an angle of 90.degree.. When the belt webbing portions extend from the clamping mechanism at an angle of 90.degree., the clamping mechanism can effectively clamp across the full width of the webbing portions.
However, depending on the size of the vehicle occupant and the position of the vehicle seat, the lap and torso portions of the belt webbing may not extend straight back from the trailing end portion of the tongue assembly as described above. Further, the lap and torso portions of the belt webbing may extend from the trailing end portion at an angle to each other. Thus, the belt webbing portions may not extend from the clamping mechanism at an angle of 90.degree.. When a belt webbing portion extends from the clamping mechanism at an angle other than 90.degree., undesirable stresses are placed on the belt webbing, and the edges of the belt webbing can become more susceptible to tearing.
A three-point continuous loop seat belt system may sometimes be used to secure a child seat in the vehicle seat. In this case, it is necessary to fix the length of the lap portion of the belt webbing, so that the child seat can not move relative to the vehicle seat. Thus, it is desirable that a tongue assembly for a three-point continuous loop seat belt system be suitable for securing a child seat. It is also desirable that the belt webbing run relatively freely through the tongue assembly when the tongue assembly is adjacent a D-ring, so that the belt webbing can be completely stowed on the associated retractor.